The proposed 2-year investigation aims to identify factors contributing to substance use (SU) by Latino and Euro American youth, two adolescent-groups at high risk for using substances. The objectives will involve testing the causal model of SU initiation and escalation. This model specifies the operation of key proximal factors in conjunction with supported general and underlying distal factors. Consistent with the theory of triadic influence (TTI), proximal factors will include substance use related intentions, self-efficacy, attitudes, and social norms. Also consistent with TTI, distal factors include global expectancies, depression, coping strategies, parental relatedness, and academic orientation. Finally, potentially vital sociocultural influences will be conceptualized as ultimate factors (most distal to SU within TTI). Global expectancies and cultural orientation in Latinos are two especially promising factors of emphasis that have been understudied within comprehensive theory-guided models of youths' SU. The aims will be accomplished through secondary data analyses of cohorts from two studies--the Middle School Healthy Kids and Tobacco Survey (N = 1622) and the Add Health Study (N = 12,118); both datasets have Latinos and Euro American youth representing the majority of participants. The former is led by the Principal Investigator, with data collection (coordinated by ETR Associates in Santa Cruz, CA) to be completed by December 1, 2000; the latter is a national study of adolescent health sponsored by NIDA and many other federal agencies. Each dataset from these studies afford very strong tests of the model, including tests of the prediction of changes in SU over time. Collectively these data present a unique opportunity to test the model in multiple Latino sub-groups, and include reports of alcohol, tobacco, marijuana and other drugs by the youths and others they know. Cutting edge analysis techniques appropriate for longitudinal data such as structural equation, survival, and multi-level modeling will be employed to test the hypotheses. This research has the potential to directly benefit SU prevention efforts. Previous research suggests that programs addressing a both proximal and more distal factors may result in stronger, more sustained reductions in adolescent SU. However, there is currently insufficient knowledge of the key determinants, especially as they relate to high-risk Latino and Euro American youth. By clarifying how causal paths leading to substance use may be impacted by socio-cultural influences, the proposed project will also aid in the development of more potent youth intervention programs for diverse youth.